Now to the new fallout from the royal caribbean cruise cut short when hundreds on board got sick from a fast-moving virus. The situation on ship may be worse than what we've been hearing so far and linsey Davis has the latest. Reporter: New concerns as the royal caribbean "Explorer of the seas" speeds back to New Jersey two days ahead of schedule. Passengers telling us the number of sick actually spiked much higher than the roughly 600 initially reported by the cruise line. A lot of people took it upon themselves to stay in their rooms and wait it out and so the number reported doesn't reflect how many people were really sick. Reporter: Overnight royal caribbean tells ABC news "All guests on this week's cruise will receive a 50% refund of their cruise fare and an additional 50% future cruise credit. We will also reimburse airline change fees and accommodations for guests whose travel home was inconvenienced by the change of travel plans." The usuallying busting royal promenade deserted. The crew added sanitation masks as they scrub and disinfect. Everybody was so nervous they were staying to their state rooms. Reporter: Officials say this is likely a case of the highly contagious norovirus, which probably came on board with a sick person or in contaminated food. Norovirus survives on surfaces and on hands. It is a virus that is very hard to disinfect. Up to two to three weeks after you start feeling better you still are considered contagious. Reporter: CDC inspectors will remain on board the ship until it arrives in New Jersey tomorrow. For the thousands aboard the ship now, it's a vacation that can't end soon enough. For "Good morning America," linsey Davis, ABC news, new York.

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